(a) Field of the Invention
This invention relates to a rotary snapping device wherein a snap supported rotatably on a spindle as inclined so as to make an angle with the center axis of the spindle is rotated around the above mentioned center axis while holding the angle of inclination so as to be able to apply a snapping work to a rivet or the like.
(b) Description of the Prior Art
According to this kind of snapping device, the snapping work is made by rotating the spindle while pressing the tip of the snap against such part to be worked as a rivet. As the snap is fitted to the spindle through bearings so that the tip of the snap may be positioned at the intersection of the center axis of the spindle with the center axis of the inclined snap, when the spindle is rotated while the snap tip is pressed against the part to be worked, the tip will rotate while rolling on the part to be worked. By the rotary and rolling motions of this snap tip, the part to be worked will be rolled and thereby the snapping work will be made.
Therefore, this snapping method has such many advantages that such noise as in an impact snapping method is not caused. However, in the conventional device, as the snap rotates while rolling, a slip motion is generated between the snap and the part to be worked. There has been a defect that, as this slip motion acts to tear the part to be worked, a fine finished surface can not be obtained. Further, in the conventionaldevice, an oil pressure or air pressure has been utilized to move the spindle in the vertical direction and an electric motor has been utilized to rotate the spindle. The utilization of the oil pressure or air pressure has an advantage that, as the lowermost position of the spindle can be accurately regulated with a stopper, it is very easy to determine the lowermost position of the spindle and to set the finished dimensions of the worked part. However, there has been a defect that, as a fluid compression controlling means to obtain a proper oil pressure or air pressure is required and the leakage of the fluid must be well prevented, the device itself is costly. Particularly, in the case of utilizing the air pressure, there have been disadvantages that not only the detrimental substances contained in the exhaust pollute air and deteriorate the working environment but also the power loss is large. Therefore, there is already suggested a system wherein the spindle is moved in the axial direction while being rotated by an electric motor. However, in such a system, inasmuch as a power transmitting mechanism is formed by a pin-slot connection, there has been a defect that the working to form a slot is difficult and the entire construction becomes complicated.